High and medium gain antennas that can be scanned or can produce multiple simultaneous beams are needed for a variety of mobile communications and sensor applications. Typically, the mechanical or electronic systems required to scan the antenna or produce multiple beams are bulky, complex, and expensive.
Conventional scanning lens antennas use a dielectric lens to collimate the spherical wave from a small (low gain) radiator into a narrow beam (higher gain) plane wave. Shifting the location of the feed point of the radiator will scan the antenna beam over limited range of angles. Pattern quality is a function of the focal distance. A thin lens with a long focal length minimizes pattern distortions but will lose power due to spill over and will require a large rigid structure to support the lens and radiator. Shortening the focal distance requires a more complex series of lenses or results in spherical aberrations.
Therefore, there exists a need for a lens antenna that does not exhibit spherical aberrations, has minimal focal length and has a low level of complexity, thereby being cheaper to produce and implement.